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8.1 KiB
HTML
126 lines
8.1 KiB
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<meta name="DC.Type" content="task" />
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<meta name="DC.Title" content="Share tape library resources" />
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<meta name="abstract" content="Because library devices can be shared among multiple systems and users, it is possible to run more jobs that use a tape library than there are resources in the library." />
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<meta name="description" content="Because library devices can be shared among multiple systems and users, it is possible to run more jobs that use a tape library than there are resources in the library." />
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<meta name="DC.Relation" scheme="URI" content="rzam4config.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2004, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2004, 2006" />
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<meta name="DC.Identifier" content="rzam4share" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Share tape library resources</title>
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</head>
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<body id="rzam4share"><a name="rzam4share"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Share tape library resources</h1>
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<div><p>Because library devices can be shared among multiple systems and
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users, it is possible to run more jobs that use a tape library than there
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are resources in the library.</p>
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<div class="section"><p>As users send commands to the tape library, requests to use a
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resource are sent to a tape resource manager. The request waits until a resource
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becomes available. When a resource is available, the job is assigned the resource
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to complete that step. How the system handles the requests depends on the <span class="uicontrol">Properties</span> in iSeries™ Navigator
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that you specify for the tape library, or by using the Change Job Media Library
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Attributes (CHGJOBMLBA) command.</p>
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<p>To specify the <span class="uicontrol">Properties</span> for
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your tape library, do the following:</p>
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</div>
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<ol><li class="stepexpand"><span>In iSeries Navigator
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expand <span class="menucascade"><span class="uicontrol">My Connections</span> > <span class="uicontrol">your iSeries
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server</span> > <span class="uicontrol">Configuration and Service</span> > <span class="uicontrol">Tape
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Devices</span> > <span class="uicontrol">Hardware</span> > <span class="uicontrol">Tape Libraries</span></span>.</span></li>
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<li class="stepexpand"><span>Right-click the library you want to work with and select <span class="uicontrol">Properties</span>.</span></li>
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<li class="stepexpand"><span>Select <span class="uicontrol">Options</span>.</span></li>
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<li class="stepexpand"><span>Specify the options you want:</span> <ul><li>Tape resource selection priority</li>
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<li>Initial mount wait time</li>
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<li>End of volume mount wait time</li>
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</ul>
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</li>
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</ol>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzam4config.htm" title="After you have set up the tape library and connected it to your system, the iSeries server automatically configures it.">Configure tape libraries</a></div>
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</div>
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</div><div class="nested1" xml:lang="en-us" id="detailstapelibprop"><a name="detailstapelibprop"><!-- --></a><h2 class="topictitle2">Details: tape library properties</h2>
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<div><div class="section"><p>The order in which requests are given a resource is determined
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by the option you specify for <span class="uicontrol">Tape resource selection priority</span>.
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The length of time a request will wait for a resource to become available
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is controlled by the length of time you specify for the request in <span class="uicontrol">Initial
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mount wait time</span> and <span class="uicontrol">End of volume mount wait time</span>.
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The time you specify in these properties can also be set in the tape library
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device description.</p>
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<p>The character-based interface equivalent to the
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properties are the following parameters of the CHGJOBMLBA command:</p>
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<ul><li>Resource allocation priority (RSCALCPTY)</li>
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<li>Initial mount wait time (INLMNTWAIT)</li>
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<li>End of volume mount wait time (EOVMNTWAIT)</li>
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</ul>
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<p>You can use these parameters as a default or for a particular job
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using the CHGJOBMLBA command or the Change Job Media Library Attributes (QTACJMA)
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API. These values are used when a request is first sent to the resource manager.
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After a request has been sent to the resource manager and is waiting to be
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processed, it can be monitored and changed using the Work with Media Library
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Resource Queue (WRKMLBRSCQ) command.</p>
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<p>The system can automate how multiple
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library resources are shared. For example, assume ten save operations (SAVLIBs)
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are issued, with ten different cartridges, to a tape library device description
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(TAPMLB01). If TAPMLB01 has only four tape resources available to it, the
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first four requests are issued, one to each tape resource. The remaining six
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are placed on a queue and are issued as tape resources become available. The
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order in which they are placed on the queue is based on the RSCALCPTY parameter
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in the tape library device description. The resource manager eliminates any
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idle time between jobs due to early completion, from either changing data
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or job failure.</p>
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<p>You can use Initial Mount Wait Time (INLMNTWAIT) value
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to alert you of a problem. In the previous example, the ten save operations
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are started at a given time and known, through estimates or benchmarking,
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to complete in six hours. Set the INLMNTWAIT time limit to six hours. If any
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of the save operations do not complete in six hours, an escape message is
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signaled to the jobs. A pager system can monitor for this message and page
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an operator to determine the necessary recovery actions.</p>
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</div>
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</div>
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</div>
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<div class="nested1" xml:lang="en-us" id="sharetapelibresourcesbetweensys"><a name="sharetapelibresourcesbetweensys"><!-- --></a><h2 class="topictitle2">Share tape library resources between systems</h2>
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<div><div class="section"><p>You can share tape library resources between more than one system.
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Tape resources can be set to ALLOCATED, UNPROTECTED, or DEALLOCATED. To better
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facilitate sharing between systems the UNPROTECTED status was added. When
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the tape resource is set to UNPROTECTED status, the tape resource is not assigned
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until it is needed. This prevents a tape resource from being assigned to a
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system that is not presently using it.</p>
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</div>
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</div>
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</div>
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<div class="nested1" xml:lang="en-us" id="sharetapelibsamesys"><a name="sharetapelibsamesys"><!-- --></a><h2 class="topictitle2">Share tape library resources between systems and on the same system</h2>
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<div><div class="section"><p>When sharing tape resources between systems and on the same system,
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each system has a resource manager with its queue controlled by the priority
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and time-out values. Between the systems, the tape resources are set to UNPROTECTED
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status. While sharing between systems does not have a priority concept, the
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UNPROTECTED status and the fact that tape resources are only assigned when
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they are in use allows the systems to effectively share the tape resources.
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The resource manager tries to get a resource by attempting to assign it. If
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another system has the resource, the job is placed back in the queue and waits.
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In a few seconds another assign is attempted. If the job now gets the resource,
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the tape operation continues.</p>
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</div>
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</div>
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</div>
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</body>
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</html>
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